Surface water is currently seriously polluted by nitrate. In this research, cobalt aluminum hydrotalcite compounds with different molar ratios were prepared with double titration method. The cobalt aluminum hydrotalcite compounds were characterized by means of X-ray diffraction and field emission scanning electron microscopy. The results show that the unique structure of hydrotalcite is formed when the molar ratio of cobalt to aluminum is 1∶1, 2∶1 and 3∶1. Cobalt aluminum hydrotalcite was used to prepare coated electrode, and the effect of electrochemical reduction of nitrate on the electrode materials was studied by linear sweep voltammetry. It is concluded that when the molar ratio of cobalt to aluminum is 2∶1, the electrochemical reduction of nitrate has the best effect, and there is a linear relationship between the peak current and the reduction of nitrate concentration and scan rate. The experimental results show that cobalt aluminum hydrotalcite coating electrode can be used in the electrochemical detection of nitrate and nitrate removal process.